Marta Dias

Effect of temperature in multiple biomarkers of oxidative stress in coastal shrimp

Various studies in captivity and in the wild have pointed to the effect of season, and temperature in particular, in the levels of the oxidative stress biomarkers currently used for environmental quality assessment. However, knowledge on how temperature affects the oxidative stress response is unavailable for most species. This study investigated the effect of increasing temperature on lipid peroxidation, catalase activity, superoxide dismutase and glutathione-S-transferase in the shrimps, Palaemon elegans and Palaemon serratus. It was concluded that increasing temperatures significantly affect all the biomarkers tested in both species, with the exception of superoxide dismutase in P. serratus which was not affected by temperature. The oxidative stress response was more intense in P. elegans, than in P. serratus, producing higher peaks of all biomarkers at temperatures between 22°C and 26°C, followed by low levels at higher temperatures. It was concluded that monitoring of ecosystems using oxidative stress biomarkers should take into account the species and thermal history of the organisms. Sampling should be avoided during heat waves and immediately after heat waves.

Characterizing the modulation transfer function (MTF) of proton/carbon radiography using Monte Carlo simulations

PURPOSE To characterize the modulation transfer function (MTF) of proton/carbon radiography using Monte Carlo simulations. To assess the spatial resolution of proton/carbon radiographic imaging. METHODS A phantom was specifically modeled with inserts composed of two materials with three different densities of bone and lung. The basic geometry of the phantom consists of cube-shaped inserts placed in water. The thickness of the water, the thickness of the cubes, the depth of the cubes in the water, and the particle beam energy have all been varied and studied. There were two phantom thicknesses considered 20 and 28 cm. This represents an average patient thickness and a thicker sized patient. Radiographs were produced for proton beams at 230 and 330 MeV and for a carbon ion beam at 400 MeV per nucleon. The contrast-to-noise ratio (CNR) was evaluated at the interface of two materials on the radiographs, i.e., lung-water and bone-water. The variation in CNR at interface between lung-water and bone-water were study, where a sigmoidal fit was performed between the lower and the higher CNR values. The full width half-maximum (FWHM) value was then obtained from the sigmoidal fit. Ultimately, spatial resolution was defined by the 10% point of the modulation-transfer-function (MTF10%), in units of line-pairs per mm (lp/mm). RESULTS For the 20 cm thick phantom, the FWHM values varied between 0.5 and 0.7 mm at the lung-water and bone-water interfaces, for the proton beam energies of 230 and 330 MeV and the 400 MeV/n carbon beam. For the 28 cm thick phantom, the FWHM values varied between 0.5 and 1.2 mm at the lung-water and bone-water interface for the same inserts and beam energies. For the 20 cm phantom the MTF10% for lung-water interface is 2.3, 2.4, and 2.8 lp/mm, respectively, for 230, 330, and 400 MeV/n beams. For the same 20 cm thick phantom but for the bone-water interface the MTF10% yielded 1.9, 2.3, and 2.7 lp/mm, respectively, for 230, 330, and 400 MeV/n beams. In the case of the thicker 28 cm phantom, the authors observed that at the lung-water interface the MTF10% is 1.6, 1.9, and 2.6 lp/mm, respectively, for 230, 330, and 400 MeV/n beams. While for the bone-water interface the MTF10% was 1.4, 1.9, and 2.9 lp/mm, respectively, for 230, 330, and 400 MeV/n beams. CONCLUSIONS Carbon radiography (400 MeV/n) yielded best spatial resolution, with MTF10% = 2.7 and 2.8 lp/mm, respectively, at the lung-water and bone-water interfaces. The spatial resolution of the 330 MeV proton beam was better than the 230 MeV proton, because higher incident proton energy suffer smaller deflections within the patient and thus yields better proton radiographic images. The authors also observed that submillimeter resolution can be obtained with both proton and carbon beams.

Physiological, cellular and biochemical thermal stress response of intertidal shrimps with different vertical distributions: Palaemon elegans and Palaemon serratus

The ability to cope with high temperature variations is a critical factor in intertidal communities. Two species of intertidal rocky shore shrimps (Palaemon sp.) with different vertical distributions were collected from the Portuguese coast in order to test if they were differentially sensitive to thermal stress. Three distinct levels of biological organization (organismal, biochemical, and cellular) were surveyed. The shrimp were exposed to a constant rate of temperature increase of 1°C x h(-1), starting at 20°C until reaching the CTMax (critical thermal maximum). During heat stress, two biomarkers of protein damage were quantified in the muscle via enzyme-linked immunosorbent assays: heat shock proteins HSP70 (hsp70/hsc70) and total ubiquitin. Muscle histopathological alterations caused by temperature were also evaluated. CTMax values were not significantly different between the congeners (P. elegans 33.4 ± 0.5 °C; P. serratus 33.0 ± 0.5 °C). Biomarker levels did not increase along the temperature trial, but P. elegans (higher intertidal) showed higher amounts of HSP70 and total ubiquitin than P. serratus (lower intertidal). HSP70 and total ubiquitin levels showed a positive significant correlation in both species, suggesting that their association is important in thermal tolerance. Histopathological observations of muscle tissue in P. serratus showed no gross alterations due to temperature but did show localized atrophy of muscle fibers at CTMax. In P. elegans, alterations occurred at a larger scale, showing multiple foci of atrophic muscular fascicles caused by necrotic or autolytic processes. In conclusion, Palaemon congeners displayed different responses to stress at a cellular level, with P. elegans having greater biomarker levels and histopathological alterations.

Intertidal pools as alternative nursery habitats for coastal fishes

ABSTRACT Fish were sampled monthly in four tidal pools, for two years, on the west Portuguese coast. Species diversity of transient fish was higher than that found in previous studies, in other parts of the world. The transient fish population comprised six species: the white seabream, Diplodus sargus, sand smelt, Atherina spp., the thinlip grey mullet, Liza ramada, the Baillons wrasse, Symphodus bailloni, the zebra seabream, Diplodus cervinus and the European pilchard, Sardina pilchardus. Abundance varied seasonally, yearly, and among pools, with peak numbers in spring and summer. The most abundant species in all pools, both as larvae and juveniles, was D. sargus. Diplodus sargus and Atherina spp. were present in most pools, from spring to autumn, while rare species were present mostly in the spring-summer period. Smaller mean sizes of larvae and juveniles were observed at the beginning of spring of 2011 (March–April) and at the end of spring/beginning of summer of 2012 (May–June). Mean size of larvae and juveniles often showed a continuous increase from spring to autumn in both years. The highest density peaks were due to the high number of post-larvae entering the pools in spring. In most pools, the overall condition (Fultons K) of D. sargus increased throughout the year, in both years. The species richness, the high densities of early stages, and their continuous growth observed in tidal pools strongly emphasize the importance of these environments for larvae and juveniles of several transient marine fishes.

Use of rocky intertidal pools by shrimp species in a temperate area

Abstract Rocky shores are among the most-intensively studied ecosystems, however, tidal pools remain relatively understudied. This study aims to investigate the habitat use and dynamics of the shrimp species that occur in tidal pools of a North-eastern Atlantic coast, the Portuguese coast, in particular species composition, abundance, seasonality and size structure. Shrimps were sampled monthly from six tidal pools for one year, in the west Portuguese coast. Species diversity was much higher than that found in previous studies, in other parts of the world. The shrimp population comprised 8 species: the European rock shrimp, Palaemon elegans, the common prawn, Palaemon serratus, the Atlantic ditch shrimp, Palaemon varians, the Baltic prawn, Palaemon adspersus, the Oriental shrimp, Palaemon macrodactylus and the relatively rare shrimps Eualus sollaudi, Eualus drachi and Caridion gordoni. Shrimp populations varied seasonally and among pools, with peak numbers in spring and summer. The most abundant species was P. elegans. P. elegans was present in all pools, throughout most of the year. Rare and exotic species were present mostly in spring-summer. Lower mean sizes of all shrimp were registered in the beginning of spring, most often in April or May, and gradually increased until winter. New-recruits of the most abundant species, P. elegans, generally entered the pools in spring and formed a high proportion of the population between April and August. They were responsible for the highest abundance peaks of shrimps occurring in the pools. The species richness and high numbers of juveniles occurring in tidal pools suggest that these environments may be nursery areas for coastal shrimp.

Ecological traps in shallow coastal waters—Potential effect of heat-waves in tropical and temperate organisms

Mortality of fish has been reported in tide pools during warm days. That means that tide pools are potential ecological traps for coastal organisms, which happen when environmental changes cause maladaptive habitat selection. Heat-waves are predicted to increase in intensity, duration and frequency, making it relevant to investigate the role of tide pools as traps for coastal organisms. However, heat waves can also lead to acclimatization. If organisms undergo acclimatization prior to being trapped in tide pools, their survival chances may increase. Common tide pool species (46 species in total) were collected at a tropical and a temperate area and their upper thermal limits estimated. They were maintained for 10 days at their mean summer sea surface temperature +3°C, mimicking a heat-wave. Their upper thermal limits were estimated again, after this acclimation period, to calculate each species’ acclimation response. The upper thermal limits of the organisms were compared to the temperatures attained by tide pool waters to investigate if 1) tide pools could be considered ecological traps and 2) if the increase in upper thermal limits elicited by the acclimation period could make the organisms less vulnerable to this threat. Tropical tide pools were found to be ecological traps for an important number of common coastal species, given that they can attain temperatures higher than the upper thermal limits of most of those species. Tide pools are not ecological traps in temperate zones. Tropical species have higher thermal limits than temperate species, but lower acclimation response, that does not allow them to survive the maximum habitat temperature of tropical tide pools. This way, tropical coastal organisms seem to be, not only more vulnerable to climate warming per se, but also to an increase in the ecological trap effect of tide pools.

Ion Radiography as a Tool for Patient Set-Up & Image Guided Particle Therapy: A Monte Carlo Study:

This study investigate the use of ion radiography as a tool for patient set-up and tumor tracking capabilities for image guided particle therapy (IGPT) using Monte Carlo simulations. One pediatric, two lung and one liver cancer patients were considered in this study. For each patient, 230 and 330 MeV proton, and 500 MeV/nucleon carbon ion pencil beams were simulated through their computed tomography (CT) data set using GEANT4.9.0. Energy, position and direction cosines of each particle were recorded in front and behind the patient. Ion radiographs were subsequently reconstructed using a dedicated in-house software. The image quality was assessed by evaluating the contrast-to-noise ratio of the tumor and its surrounding tissue. In the lung and liver cases, each CT phase of the breathing cycle was treated individually and dynamic sequences were later produced to appreciate tumor motion. Reconstructed radiographs show high spatial resolution. This allows for excellent imaging capabilities in pediatric patients, comparable to X-ray imaging at a fraction of the imaging dose. There is clear visualization of the tumor edges in the lung due to the great contrast-to-noise ratio between the tumor and its surrounding tissues; tumor motion is observed and comparable to 4D CT data thus allowing for on-line tumor tracking during ion radiotherapy. Conversely, tumor edge detection is difficult in liver, and fiducial markers are required to attempt indirect tumor tracking for IGPT. Ion radiographs with high spatial resolution can be generated using the PR-creator software resulting in pediatric patient set-up capabilities at a fraction of the current imaging dose, as well as the capacity to track moving targets in order to achieve IGPT.

TH‐E‐220‐04: IGPT Using Proton Radiography: A Monte Carlo Study

Purpose: To evaluate the feasibility of image guided protonradiotherapy (IGPT) using direct or indirect tumor tracking (tumor itself or fiducial markers) with on‐line protonradiographyimaging using Monte Carlo simulations. Methods and Materials: This study considered two lungcancer patients and one livercancer patient. For each patient, 230‐ and 330‐MeV proton pencil beams were simulated through each of the ten CT phases of their breathing cycle using the GEANT4 Monte Carlo toolkit. Energy, position and direction cosines of each particle were recorded in front and behind the patient, and protonradiographs were reconstructed using a novel algorithm. These radiographs correspond to on‐line images that could be acquired during treatment by quickly changing the proton beam energy. Image sequences were finally generated using the protonradiographs in order to reproduce the breathing cycle of each patient. Results: Lungtumorradiographs, with high spatial resolution (∼1.2–1.6mm), show great contrast‐ to‐noise ratio between the tumor and its surrounding tissues, thence allowing for clear visualization of the tumor edges. Conversely, the livertumors density is very similar to its background, and is therefore hard to discern; only the high Z fiducial markers are visible. For both lungcancer patients, direct tumor motion is clearly observed, and comparable to 4DCT data (∼0.5–1cm), hence allowing for on‐line tumor tracking during protonradiotherapy. The results also show that indirect tumor tracking using the fiducial markers would be a viable technique for other tumor cases such as livercancer. Conclusion: It was shown that IGPT using tumor tracking would be feasible using protonradiography by quickly changing the proton beam energy during treatment. The implementation of such technology could further lead to adaptive protonradiotherapy, and further improve irradiation treatments. Due to their intrinsic better imaging properties, carbon ion beam are also under investigation.

What's in a tide pool? Just as much food web network complexity as in large open ecosystems

Understanding the fundamental laws that govern complex food web networks over large ecosystems presents high costs and oftentimes unsurmountable logistical challenges. This way, it is crucial to find smaller systems that can be used as proxy food webs. Intertidal rock pool environments harbour particularly high biodiversity over small areas. This study aimed to analyse their food web networks to investigate their potential as proxies of larger ecosystems for food web networks research. Highly resolved food webs were compiled for 116 intertidal rock pools from cold, temperate, subtropical and tropical regions, to ensure a wide representation of environmental variability. The network properties of these food webs were compared to that of estuaries, lakes and rivers, as well as marine and terrestrial ecosystems (46 previously published complex food webs). The intertidal rock pool food webs analysed presented properties that were in the same range as the previously published food webs. The niche model predictive success was remarkably high (73–88%) and similar to that previously found for much larger marine and terrestrial food webs. By using a large-scale sampling effort covering 116 intertidal rock pools in several biogeographic regions, this study showed, for the first time, that intertidal rock pools encompass food webs that share fundamental organizational characteristics with food webs from markedly different, larger, open and abiotically stable ecosystems. As small, self-contained habitats, intertidal rock pools are particularly tractable systems and therefore a large number of food webs can be examined with relatively low sampling effort. This study shows, for the first time that they can be useful models for the understanding of universal processes that regulate the complex network organization of food webs, which are harder or impossible to investigate in larger, open ecosystems, due to high costs and logistical difficulties.

RAZÕES PARA ACOLHER PESSOAS REFUGIADAS: DAS REPRESENTAÇÕES À AÇÃO

Este estudo pretende apresentar um processo de investigacao e intervencao comunitaria dedicado a problematica das pessoas refugiadas, desde a fase embrionaria de geracao de ideias, estabelecimento de contactos, angariacao de apoios, as fases de investigacao, planificacao, execucao, avaliacao e follow-up, levado a cabo por uma turma do Curso Tecnico Superior Profissional de Animacao Sociocultural aplicada ao Ecoturismo, com duas professoras do curso, na Unidade Curricular Fundamentos e Metodologias de Animacao Sociocultural. Palavras-chave: Refugiados, migracoes, projeto, animacao, cultura, Portugal, Europa.